import json
import datetime

#对单个模型操作
def model_to_dict(model, fields=None):
    """
    将Flask SQLAlchemy的模型对象转换为字典类型
    :param: model : 模型对象
    :param: fields : 需要获取的字段列表，默认为 None，获取全部字段
    :return: 返回字典类型
    """

    if fields is None:
        # 获取所有列名
        columns = [column.name for column in model.__table__.columns]
        # 排除掉relationships 设置的反向查询字段
        relations = getattr(model.__class__, '__mapper__').relationships
        exclude_cols = [rel.key for rel in relations]
        # print(exclude_cols,'要剔除的反向查询字段')
        #拿到所有列名-排除的列名
        cols = set(columns) - set(exclude_cols)
        fields = list(cols)

    obj_dict = {}
    for field in fields:
        if field not in model.__dict__:
            continue

        value = model.__dict__[field]
        #1、对时间字段进行操作
        if isinstance(value, datetime.datetime):
            #字段类型是datetime的，格式化
            value = value.strftime('%Y-%m-%d %H:%M:%S')
        if isinstance(value,datetime.date):
            #字段类型是date的，格式化
            value = value.strftime('%Y-%m-%d')
        #2、将所有可以进行序列化的进行序列化
        if isinstance(value,str):
            try:
                value = json.loads(value)
            except Exception as _:
                pass

        obj_dict[field] = value

    return obj_dict

#对数据集操作
def model_to_dict_list(queryset,fields=None):

    ret = []
    for obj in queryset:
        dic = model_to_dict(obj,fields=fields)
        ret.append(dic)
    return ret